Many electrical devices require connection with the electrical circuits of other electrical devices in order for them to function properly. Indeed, it is not uncommon for an electrical device to require simultaneous connection with a great many electrical circuits in other devices. To satisfy this requirement, connectors have been developed that can establish as many as seven or eight hundred different electrical circuits between electrical devices. Commonly used terms for such connectors include: "pin grid array" and "land grid array".
Typically, a grid array will include a generally flat base member, and will have a multitude of individual electrical connectors. For most applications, these connectors are mounted as an array on the base member and extend from both sides thereof to establish as many different electrical pathways through the base member of the array.
A commonly used component for the individual electrical connectors of a land grid array is a deformable, electrically conductive, wire mesh structure known as a "fuzz button". In addition to establishing an electrical pathway, an important attribute of these so-called fuzz buttons is that they are inherently resilient and flexible. This resilience and flexibility, however, can be both beneficial and detrimental to the performance of the land grid array.
On the one hand, resilience and flexibility in an electrical connector are desirable in that these qualities promote the proper engagement of an electrical connector with an electrical device. For instance, some relative movement between the connector and the device is beneficial for causing a "wiping" action which helps assure electrical contact between the device and the connector, and thereby establish the electrical pathway through the connector. Further, some flexibility between electrical components is advantageous in order to accommodate variations in the tolerances that are engineered into electrical devices. Although fuzz buttons are generally highly deformable, and easily accommodate tolerance variations, they can become misshaped with extended, repetitive use. Thus, they can give uneven contact pressures between the various electrical contact points. For the same reason, fuzz buttons are prone to loosing their registration with the contact points on the electrical connector to which they are mated. With either uneven contact pressures or lost registration, essential electrical circuits may not be established by the land grid array. To overcome these shortcomings, other electrical contact structures need to be considered.
Electrical contact fingers which are mounted on base members, and which are cantilevered therefrom, have certain structural attributes which are beneficial to an electrical connector. First, a cantilevered contact finger can be engineered to have a requisite flexibility. Second, the finger can be engineered to maintain structural integrity and dependability over a prolonged duty life. Further, when used within engineered limitations, solid fingers are minimally susceptible to becoming deformed or misshaped. Thus, they are able to effectively maintain their strength and their ability to be repetitively repositioned in register.
In addition to flexible connectors, it is also often desirable to have more solid and permanently established electrical contact points incorporated into a connector assembly. Soldering is a well known technique for establishing such contact points. However, in order to establish solder points where numerous such points must be simultaneously established, it is necessary to accurately register the solder points and to have them properly connected between other circuitry.
An important concern for electrical connectors involves the mechanical forces which are generated against the electrical components when they are electrically joined to each other via the connector. For the particular instance of a land grid array scheme where opposed flexible contact points is to be used to connect one electrical device with another, the forces which are required to establish and maintain the connection between electrical components can be considerable. Specifically, for land grid array schemes which use one cantilevered beam to establish electrical contact with one device and an opposed cantilevered beam to establish electrical contact with another device, when both beams are between the devices the forces which are respectively generated by the two beams will be additive. Consequently, the resultant force against each of the electrical components is the sum of the separate forces that are generated by the two individually deflected beams. For many applications, this resultant force may be too large. However, if one of these beams is replaced with a solder connection, which involves no interactive forces, the force of the replaced beam will be effectively eliminated. The resultant force on the electrical components will thereby be effectively halved.
In light of the above, it is an object of the present invention to provide a land grid array which will establish reliable electrical circuits, despite repeated use over a prolonged period of time. Another object of the present invention is to provide a land grid array connector which effectively maintains registration for a plethora of electrical circuits. Still another object of the present invention is to provide a land grid array connector which is adaptable for engagement with different types of electrical devices. Another object of the present invention is to provide a land grid array connector which incorporates both flexible contact pin connectors and fixed solder points in the same electrical connector assembly. It is also an object of the present invention to provide a land grid array connector which tends to minimize the resultant forces that are generated by the connector assembly against the electrical components it is interconnecting. Yet another object of the present invention is to provide a land grid array which is simple to use, relatively easy to manufacture and comparatively cost effective.